Intended to flavor and preserve food, liquid smoke is a condiment that is made from the process of capturing smoke released by burning a certain type of wood such as hickory inside a condenser. The smoke is then cooled until it forms into water, and mixed with flavors that vary with each manufacturer.
According to B&G.com, Wright's liquid smoke, a brand that is sold in retailers across the nation, contains only three calories per tablespoon. In addition, Wright's liquid smoke does not contain sodium, preservatives or sugars and is all natural.
According to practicallyedible.com, liquid smoke can contain other ingredients in addition to water and smoke concentrate. These include vinegar, molasses, caramel, sugar and various spices. It is important to check the label of each liquid smoke product to ensure individual safety against specific allergies.